This invention relates to pulse radar systems, and more particularly, an apparatus and method for measuring the RF carrier frequency of a stream of pulse RF signals.
Radar and electronic warfare system commonly employ pulse RF signals with narrow pulse widths and low duty cycles. Such systems demand accurate knowledge of the RF carrier frequency. Existing automated techniques include pulse RF frequency counters, spectrum analyzers, synchronous detectors, and digital frequency discriminators, among others. These techniques cannot provide the required frequency measurement accuracy for current state-of-the-art radar and electronic warfare systems.
Pulse frequency counters, due mainly to gate jitter, can provide 500 Khz accuracy for a 100 ns pulse width signal. Synchronous detectors are limited to 10 Khz measurement accuracy for a 100 ns pulse width signal. Digital frequency discriminators can provide 100 Khz measurement accuracy for a 100 ns pulse width signal. Each of these techniques require substantial additional hardware to typical electronic warfare and radar automatic measurement systems. The spectrum analyzer is also limited in measurement accuracy for narrow pulse widths. The spectrum analyzer accuracy for 100 ns pulse width is typically 150 Khz.
It is an object of the invention to provide a measurement of the RF frequency of a stream of pulse RF signals utilizing a spectrum analyzer or other such systems with improved resolution.